New York grouse drumming survey offers a glimpse into bird numbers
Albany — One of DEC’s chief gauges of the statewide ruffed grouse population comes from, ironically, spring turkey hunters.
That annual grouse drumming survey is more a product of sounds than sightings; turkey hunters tally the number of grouse they hear drumming during the bird’s breeding season in May.
The results show a per-hour “drumming rate” and changes in that rate from one year to the next serve as one barometer of the grouse population various regions of the state.
Bottom line, there’s often a link between the spring drumming rate and the fall flushing rate for grouse hunters.
“We anticipate that the flush rate during the upcoming season will be slightly higher than last fall,” said DEC wildlife biologist Mike Schiavone said in his 2018 spring drumming report. “Despite severe winter conditions in March in many regions, the winter was relatively mild in most of the state, with the exceptions of the Adirondacks-Tug Hill ecozone.”
Schiavone added that nesting conditions were relatively dry in May and June across much of the state, which is “a good sign for nest and chick success.”
Schiavone said that while the drumming report offers a glimpse into grouse numbers, it doesn’t always translate to flush rates in the fall. “Part of the reason for this may be the unpredictability of the nesting season between the time the survey is conducted in the spring and the time the grouse log is conducted during the fall,” he said, pointing to the nesting success and survival of grouse broods.
Statewide, 217 spring gobbler hunters participated in this year’s drumming survey, reporting data from nearly 2,000 hunting trips and hearing over 1,300 drumming grouse.
Among the 2018 survey’s findings:
- hunters participating in the survey averaged about 33 hours afield during the 2018 season. They took about nine trips afield for the season and spent almost four hours afield per trip.
- survey participants averaged about six grouse observed per hunter for the 2018 season and had to spend 5½ hours afield in order to hear one grouse drumming.
- about two-thirds of all survey effort took place during the first two weeks of May, but the drumming rate (grouse drumming per hour) was highest during the third week of the month.
- overall, there was far more effort expended in the state’s Southern Zone (about 85 percent of the total), but the drumming rate was higher in the northern zone (0.38 versus 0.21 grouse drumming/hour).
Significantly more effort was expended, and more grouse were observed, on private land than public land. However, the drumming rate was similar on public and private lands.
- the highest drumming rate was heard in DEC’s Region 6 in the St. Lawrence Valley/western Adirondacks (0.50 grouse drumming/hour) followed by DEC Regions 5, 7 and 9 (0.23-0.26 grouse drumming/hour).
- the drumming rate was below the statewide average in DEC Regions 3, 4 and 8 (0.05, 0.18, and 0.19 grouse drumming/hour, respectively).
- the drumming rate was highest in the St. Lawrence Valley Ecozone (0.57 grouse drumming/hour), followed by the Adirondacks-Tug Hill and Appalachian Hills and Plateau ecozones (0.43 and 0.31 grouse drumming/hour, respectively).
- the drumming rate was close to the statewide average in the Catskills-Delaware Hills and Champlain Valley ecozones, and below average in the Mohawk Valley-Hudson Valley-Taconic Highlands and Lake Plains ecozones.
Over the past 12 years, grouse numbers increased, peaked around 2009, and have declined since, Schiavone’s report said.
“Whether this is a result of some cyclical fluctuation or is related to the influence of habitat and weather on nest and brood success is unknown,” he said. “A similar pattern has been observed in the flush rate from the Grouse and Woodcock Hunting Log conducted during the fall, providing evidence that changes in the drumming rate reflect changes in abundance over time.”
Between 2017 and 2018, the drumming rate increased in the Appalachian Hills and Plateau and Champlain Valley ecozones and decreased in the Adirondacks-Tug Hill and St. Lawrence Valley ecozones. It was similar in the Catskills-Delaware Hills, Lake Plains, and Mohawk Valley-Hudson Valley-Taconic Highlands ecozones. The drumming rates in the Lake Plains and Hudson Valley regions have been consistently below the statewide average over the past 12 seasons.
Schiavone’s report said annual variations in grouse abundance “are likely a result of variation in weather, including spring temperature and rainfall and winter snow conditions, and food availability during the summer and fall (e.g., hard and soft mast, insects).”
Habitat also plays a key role in grouse abundance.
“In areas with a lack of the early successional habitats on which this species depends (e.g., Lake Plains, lower Hudson Valley), grouse, their nests, and young are more vulnerable to predation and other limiting factors,” the report read. “Over the past 12 years, the Wildlife Management Units with the highest drumming rates are those that have a landscape with a greater proportion of the early successional habitats (e.g., shrub land, young forests) that grouse depend upon.”